RU2333937C2 - Method for producing high-octane petrol - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the field of oil refining and can be used for production of high-octane automobile petrols. The method of producing high-octane petrol includes obtaining straight-run petrol of fraction NK-180°C, which is supplied to stabilisation column. Obtained stable petrol is subjected to fractioning in column of clear rectifying into light fraction NK-85°C and heavy fraction 85-180°C, the former being supplied to isomerisation, and the latter to reforming. Then isomerisate and catalisate are mixed to obtain commercial petrol. Stable petrol received from the bottom of stabilisation column is cooled to temperature of 130-150°C by means of two heat-exchangers installed on the line of raw material introduction into rectifying column. Fractioning is carried out at temperature of rectifying column bottom equal to 160-177°C and pressure of 2.3-2.8 kg/cm², and, of column top, at temperature of 93-113°C and pressure of 2.1-2.6 kg/cm, irrigation consumption being 140 to 180 m³/hour. Light fraction NK-85°C is supplied to isomerisation with end of boiling of 72-74°C according to Engler, while heavy fraction 80-185°C is supplied to reforming with beginning of boiling of 100-102°C according to Engler. As petrol components of secondary refining processes are not used and introduction of expensive additives (ethers) and toxic additives (tetraethyllead) is excluded, the claimed method is the most economical.

EFFECT: elaboration of efficient and economical method for producing high-octaine petrol.

6 tbl, 2 dwg

Description

The invention relates to the field of oil refining and can be used in the production of high-octane gasoline.

A known method of producing high-octane gasoline (1), which consists in the fact that the straight-run gasoline fraction NK-160 ° C is subjected to hydrotreating, and then fractionated to obtain the NK-85 ° C and 85 ° C-KK fraction, the NK-85 ° C fraction is subjected isomerization with the formation of isomerizate, and the fraction of 85 ° C-KK is subjected to catalytic reforming.

A distinguishing feature of the known technical solution is the fractionation of catalytic reforming gasoline into 4 fractions, as well as the mixing of these fractions with isomerizate in the stated ratio.

The disadvantage of this method is the additional acceleration of reforming catalysis, which leads to a complication of the process, increased costs.

In addition, there is no mechanism for controlling the benzene content.

A known method for producing a high-octane component of motor fuel (2) by hydrotreating a gasoline fraction, rectifying the liquid hydrotreating products into light and heavy or light, medium and heavy, the light fraction containing 1-15% C ₆ naphthenic hydrocarbons, and the heavy fraction containing ≈5% the amount of hydrocarbons With ₆ .

The light fraction is isomerized, and the heavy fraction is reformed. Next, the liquid products of reforming and isomerization or the liquid products of isomerization, reforming and middle fraction are mixed. Both processes are carried out in a single circulation circuit of a hydrogen-containing gas. The separation of the middle fraction leads to a decrease in the octane number of the component, in addition, up to 5% of C ₆ hydrocarbons remain in the reforming feedstock, which leads to the production of a component with a benzene content of up to 3-5%.

There is also known a method for the production of gasoline with a reduced content of benzene (3), in which straight-run gasoline is sent to the stabilization column, then it is removed from the bottom of the stabilization column at a temperature of 180-190 ° C and fed to the secondary distillation column (clear distillation) to obtain fractions NK-100 ° C and 100-185 ° C.

The NK-100 ° C fraction is sent for isomerization, and the 100-185 ° C fraction for reforming.

Moreover, unstable gasoline is fed to the top of the stabilization column (for 39 plates), and stable gasoline is fed to the top of the clear distillation column (for 40 plates). With this embodiment of the technological scheme, good separation is achieved between light and heavy fractions.

However, in this case, in order to reduce the benzene content, distillation of the low boiling fraction NK-100 ° C from raw materials for catalytic reforming at atmospheric oil distillation units and distillation of the NK-100 ° C fraction from unstable hydrogenation in the hydrodesulfurization section of the catalytic reforming unit are used.

The yield of the NK-100 ° C fraction is 33-39% for stable gasoline. Since the NK-100 ° C fraction as a raw material of isomerization has a high boiling point, as a result, it has a high content of C ₇ hydrocarbons, which impedes the isomerization process and contributes to a decrease in the quality of gasoline produced and coke deposition on the catalyst, thereby reducing the life of the catalyst.

The closest in technical essence and the achieved result is a method for producing automotive high-octane gasoline (3), which includes obtaining straight-run gasoline of the NK-180 ° fraction, which is fed to the stabilization column, the obtained stable gasoline at a temperature of 170-195 ° C is sent to a clear distillation column and get fractions NK-85 ° C and 85-180 ° C.

The NK-85 ° С fraction is fed to condenser-coolers, then to isomerization, and the 85-180 ° С fraction is sent for reforming.

The reformate catalyst and isomerizate from the isomerization unit are mixed to produce high-octane gasoline, which is sent to commercial tanks.

In the above technical solution, stable gasoline is fed into the distillation column at a temperature of 170-195 ° C, which is equal to the temperature of the bottom of the stabilization column.

In this regard, a large proportion of distillation is observed in the evaporation zone of the column; in the distillation column, vapors rise upward, carrying a large amount of C ₇ hydrocarbons upward. As a result, additional phlegm is required to condense the latter, and the C ₆ light hydrocarbons are carried down the column, which leads to an increase in benzene-forming components in the reforming feed and in the reforming catalyst.

Benzene and aromatic hydrocarbons are the most toxic compounds that enter the atmosphere when gasoline evaporates, and when the car is running, they form carcinogens in the exhaust gases.

In this regard, for gasolines with improved environmental properties, EURO-3.4 in accordance with GOST R 5186-2002 (EN-228) (for high-octane gasolines of the grades - Euro-92 Regular, Euro-Premium Premium, Euro-98 Super and their types - I. II. III) additional parameters are introduced - the benzene content is not more than 1% vol. and aromatic hydrocarbons not more than 42% vol. for EURO-3 (type 2) and not more than 35% vol. for EURO-4 gasolines (type 3).

In the considered method, an increased content of benzene up to 3 wt.% Worsens the environmental characteristics of the resulting gasoline and requires the additional involvement of expensive high-octane components that do not contain benzene.

To achieve optimal performance in the isomerization feedstock, a restriction on the content of hydrocarbons from ₇ to 3 wt.% Was introduced. In this method, the content of C ₇ hydrocarbons can reach up to 10% by weight, which makes it difficult to involve it in the isomerization feedstock due to the high coke deposition on the catalyst.

In general, the application of the above method for producing high-octane gasoline leads to a decrease in its environmental characteristics, a decrease in the resources of reforming raw materials, and increased energy consumption.

The aim of the present invention is to develop a method for producing high-octane gasolines with improved environmental characteristics by reducing the content of aromatic hydrocarbons, including the most toxic of them, benzene, corresponding to the requirements of GOST R 51866-2002 (EN-228-99) with change No. 1.

This goal is achieved by the fact that in the method of producing high-octane gasoline, including: obtaining straight-run gasoline (fraction NK-180), which is fed to the stabilization column; the stable gasoline obtained is subjected to fractionation in a clear distillation column into light and heavy fractions (conventional names of products: “fr. NK-85” and “fr. 85-180”), the first of which is fed to isomerization, and the second to reforming, then the obtained isomerizate and catalysate are mixed to obtain marketable gasoline, according to the invention, it is cooled to a temperature of 130-150 ° C by means of heat exchangers on the feed line to the distillation column, and fractionation is carried out at the bottom temperature of the rectification column 160-177 ° C, and a pressure of 2.3-2.8 kg / cm ^2, and the top of the column - at a temperature of 93-113 ° C and a pressure of 2.1-2.6 kg / cm ^2, with return part of the top product after condensation as irrigation with a flow rate of 140-180 m ³ / h, while the top product (light "fraction NK-85") is fed to isomerization with an end boiling according to Engler 72-74 ° C, and the remainder ("fraction 85-180 ") served on reforming with a boiling point of 100-102 ° C.

In this method of producing high-octane gasoline, a platinum-rhenium catalyst is used for reforming, and a platinum catalyst on a zirconium carrier (“Par-Isom” process) is used for isomerization.

New in the proposed method is that stable gasoline leaving the bottom of the stabilization column is cooled to a temperature of 130-150 ° C in heat exchangers installed on the feed line to the rectification column, and fractionation is carried out at a temperature border of fraction separation, which provides a light fraction with a boiling point of 72-74 ° C according to Engler and a heavy fraction with a boiling point of 100-102 ° C, this division condition is carried out at a bottom temperature of the rectification column equal to 160-177 ° C and a pressure of 2.3-2.8 kg / cm ² , and the top of the column - at a temperature of 93-113 ° C and a pressure of 2.1-2.6 kg / cm ² , when part of the upper product is returned after condensation and cooling as sharp irrigation to a rectification column with a flow rate of 140-180 m ³ / h to ensure the reflux ratio (the ratio of the flow rate of acute irrigation to the consumption of the top product) within 2-3, while the top product is fed to isomerization with an end of boiling of 72-74 ° C according to Engler, and the residue is fed to reforming with the beginning of boiling of 100-102 ° C according to Angler.

The proposed method for producing high octane gasoline is as follows.

Straight-run gasoline (“NK-180 fraction”) is preliminarily obtained and stabilized in a stabilization column. The obtained stable gasoline with a temperature of 180-195 ° C from the bottom of the stabilization column is sent along the line of input of raw materials into the rectification column. On the input line, before entering the rectification column, heat exchangers are installed. Stable gasoline is passed through heat exchangers, as a result of which its temperature drops to 130-150 ° C due to heating of straight-run gasoline (“French NK-180”), then stable gasoline enters the distillation column, where gasoline is fractionated to light “NK-fraction” 85 "and heavy" fraction 85-180 ".

The main parameters of the rectification column are as follows:

- the temperature of the bottom of the column is maintained within 160-177 ° C and a pressure of 2.3-2.8 kg / cm ² ;

- the temperature of the top of the column is maintained within 93-113 ° C and a pressure of 2.1-2.6 kg / cm ² ;

- reflux number - within 2-3.

Pre-fractionation of stable gasoline before recurring in order to control the benzene content is the most economical way. The separation boundaries of the products in the fractionation column must be adjusted so that benzene and its precursors are removed from the feed of the reforming unit.

The removal of benzene precursors is proportional to the boiling point of the reforming feedstock.

During oil refining during primary processing, the products obtained at the plants are called direct gasoline (FR. NK-180), kerosene (FR. 140-240), diesel fuel (FR. 180-360), fuel oil (FR. 360-KK) . During the secondary distillation of direct race gasoline, the names of the NK-62 or NK-85 fractions, fr. 85-180 etc. based on ITC. However, when controlling the quality of fractions, the fractional composition according to Engler (GOST 1392) is determined. Angler overclocking does not match ITK overclocking. During gradual evaporation in the Angler flask, the oil product begins to boil when the temperature is reached at which its vapor pressure is equal to atmospheric pressure. The saturated vapor pressure of the mixture is equal to the sum of the partial pressures of the components of the mixture. Therefore, the Engler boiling point is higher than the boiling point of an oil product determined by ITC, since the boiling point of the lightest component is determined by ITC. Similarly, the end of boiling of an oil product, determined by Engler, will be lower than the end of boiling it when determined by ITC, because ITK is determined as the boiling point of the heaviest component of the mixture, and by Engler, the end of boiling of an oil product is determined for a mixture of a heavy component and lighter components . The acceleration will end after the evaporation of the oil product, and the pressure of its saturated vapors in the Angler flask will not be enough for it to flow out of the flask (for crushing atmospheric pressure).

For the operational management of straight-run gasoline separation and quality control of raw materials for the production of EURO gasolines, the quality criteria of isomerization and reforming raw materials (“NK-85 fractions” and “85-180 fractions”) were determined based on the friction composition according to Engler (GOST 2177-99, ISO 3405- 88, ASTM D-86), i.e.:

- "NK-85 fraction" for the isomerization feed must have a boiling end within 72-74;

- while the "fraction 85-180" - the raw material of catalytic reforming - should have a boiling point of not less than 100-102 ° C.

A content of less than 0.5% of benzene-forming hydrocarbons in the “fraction 85-180” is observed at a boiling point of at least 100 ° C, while the end of boiling of the “NK-85 fraction” must be at least 72 ° C.

The resulting "NK-85 fraction" with a boiling point not exceeding 74 ° C by Engler after cooling is fed to the isomerization unit (Par-Isom), and the "fraction 85-180" with a boiling point of not lower than 100 ° C by Engler is fed for reforming. The resulting isomerizate and catalysate are mixed in the calculated ratios to obtain marketable gasolines that are of a quality EURO gasoline according to GOST R 51866 - 2002 amended. 1 (EN-228), and sent to the finished product tanks.

Getting marketable gasoline of the Regular Euro-92 brand Component Content % vol. % wt. Catalyst from reforming unit (LF-35-21 / 1000) 60-64 64.5-68.4 Isomerizate Par-Isoma (from installation L-35-5) 36-40 31.6-35.5 Obtaining premium Euro-95 commercial gasoline Component Content % vol. % wt. Catalyst from reforming unit (LF-35-21 / 1000) 68.5-69 72.55-73 Isomerizate Par-Isoma (from installation L-35-5) 31-31.5 27-27.45

According to the proposed method, OAO LUKOIL-Nizhegorodnefteorgsintez produced a pilot industrial batch of high-octane gasolines of the Regular EURO-92 type 2 (EURO-3 according to EN-228-2000), Regular EURO-92 type 3 (EURO-4 according to EN-228 -2005), Premium Euro-95 look 2 (EURO-3 according to EN-228-2000), Premium Euro-95 look 3 (EURO-4 according to EN-228-2005).

The results of the experimental tests are shown in tables 1-6 and diagrams 1-2 (figure 1, 2).

Based on the results of the analysis of the tests, the following conclusions can be drawn:

1. When cooling stable gasoline to a temperature of 130-150 ° C, which is fed to the distillation column (table 1), the following results were obtained:

- when the cooling temperature drops below 130 ° C, the top temperature of the column decreases and part of the benzene-forming hydrocarbons remains in the bottom product of the column due to a decrease in heat supply with raw materials / The selection of the top product of the NK-85 fraction decreases, the content of C ₇ hydrocarbons in the top product, but the content of benzene-forming hydrocarbons in the lower product increases — reforming feedstock and benzene in reforming catalyst. Increase in benzene - harmful emissions into the atmosphere;

- with increasing temperature of cooling gasoline above 150 ° C in front of the column, the temperature of the top of the column increases. The top product of the column is heavier, the content of C ₇ hydrocarbons increases in it by more than 3 wt%, which leads to an increase in coke formation on the isomerization catalyst. The selection of the product from the bottom of the column will decrease (“fr. 85-180”), the resources of reforming raw materials will decrease;

- maintaining the cooling temperature of the feed of the rectification column in the range of 130-150 ° C, we obtain optimal conditions for a clear separation of straight-run gasoline into the light fraction "NK-85" and heavy "fr. 85-180 ", namely with a hydrocarbon content of C ₇ not more than 3% wt. in the light fraction "PK-85" - raw materials of isomerization and benzene-forming not more than 0.5% wt. in heavy "fr. 85-180 "- reforming feedstocks.

2. When applying irrigation to the distillation column providing a reflux ratio in the range of 2-3, the following results were obtained (table 2):

- when the reflux ratio decreases below 2, there is an increase in the content of C ₇ hydrocarbons in the upper product (“FR. NK-85”) due to an increase in the temperature of the top of the column above 113 ° C, the selection of the NK-85 fraction increases, and the coking of the isomerization catalyst increases;

- when the reflux ratio decreases above 3, the top temperature of the column decreases below 93 ° C, the C ₇ hydrocarbon content in the upper product decreases below 3% by weight, and the selection of the upper product decreases. The content of benzene-forming hydrocarbons increases by more than 1%, the emissions of benzene into the atmosphere increase with the use of gasoline obtained from this raw material;

- when applying irrigation with a flow rate that provides a reflux ratio in the range of 2-3, we get a clear separation of gasoline into the light fraction "NK-85" and heavy "fr. 85-180 ", namely with a hydrocarbon content of C ₇ not more than 3% wt. in the light fraction "NK-85" - raw materials of isomerization and benzene-forming not more than 0.5% wt. in heavy "fr. 85-180 "- reforming feedstocks.

3. Analysis of the quality indicators of marketable gasoline of the Regular EURO-92 type 2 (EURO-3 according to EN-228-2000), Regular EURO-92 type 3 (EURO-4 according to EN-228-2005), Premium Euro-95 type 2 (EURO-3 according to EN-228-2000), Premium Euro-95 type 3 (EURO-4 according to EN-228-2005) in tanks (table 3, 4, 5, 6) for compliance with GOST R 51866-2002 as amended . 1 allows you to draw the following conclusions:

- the concentration of lead in gasoline is below the sensitivity threshold of the determination method,

- the sulfur content is lower than the norm for EURO-4 gasolines (EN-228 2005), as a result, SO ₂ emissions during engine operation are reduced;

- the volume fraction of olefin hydrocarbons is almost 20 times lower, since gasoline components of secondary processing processes are not used, an increase in olefin hydrocarbons helps increase coking and gum formation in gasoline, further to engine breakdown;

- lack of oxygen - a consequence of not using expensive esters, the absence of their allocation determines the octane number, the resulting gasoline composition is ensured by the optimal content of benzene and aromatics;

- low resin concentration - a consequence of the low content of olefinic hydrocarbons, which reduces coking and tar formation in gasoline, increases the reliability of the engine;

- oxidation stability above 360 is a consequence of the low content of olefinic hydrocarbons, no resin is formed, which preserves the purity of the gasoline tract of the engine;

- the content of aromatic hydrocarbons is below the requirements of the norms, the reduction of aromatic hydrocarbons reduces the content of harmful emissions during car operation, improves the environment;

- the volume fraction of vaporized gasoline up to 70 ° C, up to 100 ° C and 150 ° C is within normal limits, contributes to normal starting properties and stable engine operation on this gasoline;

- the end of boiling is not higher than 210 ° С - gasoline is not prone to coke formation, which contributes to the stable operation of the engine and increase its resource.

In all test examples, the resulting gasoline had an octane rating corresponding to the normative indicators.

4. The studies presented in diagrams 1 and 2 (figures 1 and 2) show:

- the development of the "NK-85 fraction" with an end boiling point below 72 ° C according to Engler leads to a shortage of benzene-forming components and their excess in the "fraction 85-180" more than 1 wt.%, which does not allow to obtain a catalysis component with a benzene content below 1, 5%;

- the development of the fraction "NK-85" with a boiling point above 74 ° C according to Engler leads to an increase in the content of C ₇ hydrocarbons above 3% by weight, which leads to coking of the catalyst of the isomerization process;

- at the beginning of the boiling of the “fraction 85-180” below 100 ° C according to Engler, the content of benzene-forming hydrocarbons increases above 1%, and at the beginning of the boiling of the “fraction 85-180” above 102 ° C according to Engler the content of C ₇ hydrocarbons in the isomerization feed increases.

The technological parameters of the proposed process for the production of high-octane gasoline, given in the claims, create the balance of the distillation column for a clear separation of the "fraction NK-85" with a hydrocarbon content of C ₇ not more than 3% wt. and "fractions 85-180" with a content of benzene-forming components of not more than 1% wt., as a result of which high-octane gasolines are obtained that meet the requirements of GOST R 51866-2002 amendment 1 (EN-228).

The proposed method allows the maximum use of the resources of straight-run gasoline fractions of oil to produce high-octane gasolines that meet the modern environmental requirements of EURO-3 and EURO-4, without the use of deep oil refining (catalytic cracking) processes.

INFORMATION SOURCES

1. Russian patent No. 2119257 "Method for producing a high-octane component of motor fuel, cl. C10G 59/00, C10G 69/08, publ. 09/27/9.

2. Patent of Russia No. 2153523 “Method for producing high-octane gasoline”, cl. C10L 1/04, C10G 69/08, publ. 07/27/2000

3. “Experience in the production of motor gasolines with a reduced benzene content in LUKOILNeftohim, F,“ Oil Refining and Petrochemicals ”Moscow, 2003, No. 3, pp. 7-12.

Table number 1 The effect of the temperature of introducing stable gasoline into the fractionation column on the hydrocarbon content of the isomerization and reforming feedstocks. The temperature of the introduction of stable gasoline in the fractionation column, ° C 115 120 125 130 133 136 139 141 143 146 148 150 153 157 160 The content of hydrocarbons With ₇ in the upper product of the column ("FR. NK-85")% wt. 1.8 2.0 2.2 2,5 2.54 2,58 2.6 2.63 2.68 2.7 2.75 2,8 2.9 3.0 3,5 The content of hydrocarbons With ₇ in the upper product of the column ("FR. NK-85")% wt. 1.8 1,5 1,2 1,0 0.9 0.85 0.78 0.75 0.68 0.6 0.55 0.5 0.45 0.42 0.4 The temperature of the bottom of the column, ° C 154 156 156 158 160 162 164 166 168 170 172 177 178 178 180 The bottom pressure of the column, kg / cm ² 1.7 1.8 1.9 2.0 2.1 2,3 2,4 2,5 2.6 2.7 2,8 2.9 3.0 3,1 3.2 The temperature of the top of the rectification column, ° C 89 90 91 92 93 96 99 102 106 110 113 116 118 119 120 The pressure of the top of the column, kg / cm ² 1.7 1.8 1.9 2.0 2.1 2.15 2.2 2,3 2,4 2,5 2.6 2.7 2,8 2.9 3.0

Table number 2 Dependence of the operation of a clear distillation column on irrigation flow. Irrigation consumption, m ³ / hour 190 185 180 174 170 166 163 150 145 140 135 130 128 The flow rate of the NK-85 fraction from the top of the column 48 49 fifty 51 53 55 58 58 60 64 68 72 85 Reflux ratio four 3.8 3.6 3.4 3.2 3 2,8 2.6 2,4 2.2 2 1.8 1,5 The temperature of the top of the column, ° C 87 90 93 88 91 93 96 one hundred 110 113 116 118 120 The content of hydrocarbons With ₇ in the upper product ("FR. NK-85"),% wt. 2,4 2.45 2,5 2,55 2.6 2.65 2.7 2.75 2,8 2.9 3.0 6.5 10.7 The content of benzene-forming hydrocarbons in the reforming feedstock (FR. "85-180"),% wt. 1,5 1,0 0.95 0.9 0.82 0.76 0.7 0.6 0.55 0.5 0.45 0.42 0.4

Claims (1)

The method of producing high-octane gasoline, including the production of straight-run gasoline fraction NK-180 ° C, which is fed to the stabilization column, the obtained stable gasoline is fractionated in a clear distillation column into a light fraction NK-85 ° C and a heavy fraction 85-180 ° C, the first of which are fed for isomerization, and the second for reforming, then the obtained isomerizate and catalysate are mixed to obtain marketable gasoline, characterized in that the stable gasoline leaving the bottom of the stabilization column is cooled to a temperature of 130-150 ° C by means of two heat exchangers installed on the feed line to the rectification column, and fractionation is carried out at a bottom temperature of the rectification column equal to 160-177 ° C and a pressure of 2.3-2.8 kg / cm ² and the top of the column at a temperature equal to 93-113 ° C, and a pressure of 2.1-2.6 kg / cm ² , with an irrigation flow rate in the range of 140-180 m ³ / h, while the light fraction NK-85 ° C is fed to isomerization with the end of boiling 72-74 ° C according to Engler, and the heavy fraction of 80-185 ° C is fed for reforming with a boiling point of 100-102 ° C according to Engler.

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